### Output Format:
You must output valid JSON. Do not add markdown or conversational text. Three fields:
- answer: Answer to the problem. Letter (A-H) identifying which of the presented choice images best completes the sequence matrix described. 
- confidence: Confidence in your answer, ranging from 0.0 to 1.0. (1.0 meaning absolutely confident, 0.5 meaning not so sure, 0 meaning purely guessing, etc.)
- rationale: Short version of the rationale for your answer.

### Example 1:
{
"answer": "H",
"confidence": 0.96,
"rationale": "Across each row, the shape gains one additional element from left to right, and the missing panel must continue this progression. Option H correctly adds the next element while preserving shape type and orientation, unlike the other options."
}

### Example 2:
{
"answer": "A",
"confidence": 0.91,
"rationale": "In each column, the pattern alternates between filled and outlined shapes while maintaining the same geometry. Option A is the only choice that matches this alternating fill rule and the established spatial alignment."
}